How do I get this character to follow its walking path?
You've confused Object Constraints with Bone Constraints. 

If you want your armature to follow a path you need to give your armature a Follow Path constraint. If I check the Properties panel > Object Constraints tab, I don't see any Follow Path. Actually you've assigned a Follow Path to one of your bones, Ankle.L, you will see it if you switch to Pose mode, select this bone and click on the Bone Constraints tab.

So delete the bone's Follow Path constraint and give a Follow Path constraint to your armature. After that press AltG to make your armature stick to the beginning of the path.